JPS60216214A - Detecting system of position - Google Patents

Abstract

PURPOSE:To achieve a high resolution by constructing a phase-locked loop so that the phase difference between a position signal varying in the shape of a sine wave and an output signal of a sine wave oscillator provided separately is made zero, and by adopting the control amount of said loop as a position signal. CONSTITUTION:Outputs ealpha and ebeta from a position signal pickup are inputted together with outputs ealpha' and ebeta' of D/A converters 14a and 14b to an adder-subtracter 8 through multipliers 7a and 7b, and a voltage (e) (DELTAtheta) proportional to the phase difference DELTAtheta between them is inputted to a counter 11 through VCO9 and a direction discriminator 10. Then, a memory address of a storage circuit 13 is given through a latch circuit 12, and the data thereof are outputted to the circuits 14a and 14b. Thereby the voltages ealpha' and ebeta' of phases coinciding with the phases of the outputs ealpha and ebeta are outputted from the circuits 14a and 14b, and thus the control amount at that time, in other words, the data of the counter 11, can be made a rotational angle of a motor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high-resolution position detection method in a motor drive device using a pulse generator as a detector.

[Prior art and its problems]

When using a pulse generator as a position detector,
The configuration is shown in FIG.
Detected by. The slits or the magnetized bodies have a phase shift of π/2 from each other. Position detection signal (5a) of position signal pickup (3).

(5b) is shaped by a pulse shaping circuit (4) and converted into a two-phase rectangular wave signal shown in (6a) and (6b) in FIG.

Therefore, each time the slit or the magnetized body crosses the position signal pink-up, a two-phase rectangular wave is generated, and the position (or rotation angle) can be detected by measuring the number of pulses.

The resolution of position detection is determined by the number of slits or magnetized bodies, and the limit for a motor control pulse generator is 10,000 pulses per revolution.

Conventionally, as a method for increasing the resolution, there was a method of taking the exclusive OR of the two-phase rectangular waves and quadrupling it, but it was impossible to further increase the resolution. [Object of the Invention] This book The purpose of the invention is to provide a position detection method that can achieve high resolution even though a conventional pulse generator is used as a position detector for submicron control of machine tools, etc. or high-precision robot control. That is.

[Structure of the invention]

The present invention configures a phase-locked loop to zero the phase difference between a position signal that changes in a sinusoidal manner and an output signal of a separately provided sine-wave oscillator, and converts the control amount of this phase-locked loop into the position signal. This is a position detection method that is characterized by:

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 2 is a block diagram showing the configuration of the position detection method according to the present invention, and the position control or speed control loops are not shown in the figure. In the figure, (7a) and (7b) are multipliers, (8)
is an adder/subtractor, (9) is a VCO (voltage controlled oscillator), (
10) is a direction discriminator, (11) is a counter, (12) is a latch circuit, (13) is a memory circuit, (14a), (
14b) is a D/A converter, (15) is a launch signal generator, and (16) is a latch circuit output signal.

First, the multipliers (7a), (7b) and the adder/subtractor (8
) phase difference detection will be explained.

Signal (5a) from position signal big amplifier (3), (
5b) as +11 formula, and e7 as shown in formula (2), respectively.
．． Let it be eB.

eg=Esinθ −1−−−−−−−−−−−−−
−fi1 formulaeB=Ecosθ −−−−−−−−−−−
----+21 formula Also, D/A converter (14a),
The output of (14b) is expressed as (3).

As shown in equation (4), let el, , e+β be respectively.

e'((=E'sin (θ−Δθ) −−−−−−−
(3) Formula e'B = E'cos (θ-Δθ) ---
-141 formula, where E and E' are the amplitude values of the position signal pick amplifier output waveform and the D/A converter output, θ is the phase, and Δθ is the phase difference.

Here, the position pink up signal (etx tee)
The phase difference (
By subtracting Δθ), it can be obtained as e (Δθ) using equation (5).

e (Δθ) = eg xe'θ−eB xejoc
=EE'(sinθcos (θ−Δθ)−cosθg
in(θ−Δθ)) −E E'sinΔθ −−−−−−−−−−−−−
---(Formula 51 phase difference Δθ is the voltage e proportional to the phase difference
(Δθ). Figure 3 shows Δθ and e (Δθ
).

Next, the phase alignment between the position pickup outputs eg, eθ and the D/A converter output signal e'tt+e'B will be explained.

The oscillation frequency of the VCO (91) is controlled by a voltage e (80) proportional to the phase difference. When the phase difference voltage is large, the oscillation frequency becomes high, and when it is small, the oscillation frequency becomes low. Fourth The figure shows the relationship between phase difference voltage and oscillation frequency.

The direction discriminator (10) detects the polarity of the phase difference, and generates a signal to count up the counter (11) if it is positive, and a signal to count down the counter (11) if it is negative.

The counter (11) provides a memory address of a storage circuit, which will be described later, by performing a count amplifier or counting down at a frequency proportional to the phase difference voltage. Also, the launch circuit (1
2) temporarily holds the counter signal and inserts it to synchronize with the timing of a microcomputer, etc.

The timing of this latch circuit is determined by the latch signal generator (15
) signal.

The latch signal generator (15) generates a launch signal at the rising or falling timing of the signal of VCO (91).

The counter data held by the latch circuit (12) is transferred to the memory circuit (12) that stores sin and cos data.
13), and the memory circuit stores the si at the given address.
n, cos data to the D/A conversion circuit (14a)
, (14b). The D/A conversion circuit generates voltages e' and e'e that vary in sin and cosine shapes at frequencies proportional to the phase difference Δθ. At this time, el,
, the phase of elβ is the output e of the position signal pink-up
A phase loop operates to match α+eIj.

At this time, it is assumed that the phase of the output e''DC+e''β of the D/A converters (14a) and (14b) is different from the phase of the output etx+eB of the position signal pink-up by Δθ. 80 is detected as a function expressed by equation (5) using multipliers (7a), (7b), and (8). When e (Δθ) is set to positive polarity, V CO (91) increases the oscillation frequency in the direction of counting up the counter (11). Therefore, the frequency at which the sin and cos data of the storage circuit are output increases, and e'tt + ``The phase of B advances. Conversely, ``1
Assuming that the phase of f+8'θ is ahead of eg and 6B by Δθ, the phase difference becomes −Δθ, and e (Δθ) has negative polarity. In this case, the counter (11) is counted down, the output frequency of the sin and cos data of the storage circuit decreases, and the phases of e+, e+θ are delayed.

As mentioned above, by increasing or decreasing the frequency due to the phase difference, the phases of e'g, e''θ can be changed to e'g, e''
Match B.

The controlled variable of this phase loop, that is, the data of the counter becomes the motor rotation angle or position.

Next, the memory circuit will be explained. The storage circuit stores pre-calculated sin and cos data.

This data is read by referring to the address of the memory circuit. This sin.

The larger the number of divisions of cos data, the higher the rotation angle or position detection resolution. For example, considering the case of division by 1000, while the counter counts from 1 to 1000, one cycle of the Sin+CoS data is sequentially output. Increase the resolution of the pulse generator to 1000 pulses/
In terms of rotation, when the pulse generator rotates for one pulse, the counter counts 1000 pulses, and when the pulse generator rotates for 1000 pulses, that is, one rotation, the counter counts 1 million pulses. This means that the resolution of the pulse generator has increased by a factor of 1000.

〔Effect of the invention〕

As described above, according to the present invention, the position resolution is dramatically improved even though a conventional pulse generator is used, and the positioning control of the electric motor can be highly accurate at low cost. It is something that plays.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the configuration and operation of a position detector using a pulse generator, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a diagram showing the phase difference 〇 and the output voltage e of the adder/subtractor.
FIG. 4 is a diagram showing the relationship between the voltage e(Δθ) and the oscillation frequency of the VCO. (1): Electric motor (2) - Detector rotating body (3): Position signal pink up (4): Pulse shaping circuit (5a), (5b):
Detection signal (6a), (6b): Pulse shaping signal (
7a), (7b): Multiplier (8): Addition/subtraction device +
91: VCO (voltage controlled oscillator) (10): Direction discriminator (11): Counter (+2
): Latch circuit (13): Memory circuit (14a),
(14b) : D/A converter (15) ; Latch signal generator (18) : Launch circuit output signal Patent applicant Yaskawa Electric Co., Ltd. Agent Handmade
Masu (1 other person)

Claims (1)

[Claims] 1. The output signal of a two-phase position detector whose amplitude changes sinusoidally according to the rotation angle of the moving object, and the output signal of a sine wave and a cosine wave.
The output signals of the voltage controlled oscillator that generates the phase output are multiplied together to obtain a DC voltage proportional to the phase difference between the two signals, and this voltage is applied as the frequency control voltage of the voltage controlled oscillator so that the phase difference becomes zero. A phase-locked loop is formed such that the output frequency of the voltage controlled oscillator is counted by a counter, and the data of the counter launched at the rising or falling timing of each waveform of the same output frequency is taken out as the rotation angle. A position detection method characterized by: